a) Field of the Invention
The present invention relates to a clamp for use to fix within an electrical device box one or two cables projecting from openings made in this box.
More particularly, the invention relates to a clamp of the above mentioned type, which is very simple yet efficient in structure, very easy and cheap to manufacture and useable to fix indifferently nonmetallic sheathed cables and/or armored cables.
In the following description and claims, the expression "electrical device box" is intended to designate any kind of boxes that are used for electrical connections, such as switch boxes, electrical outlet boxes and the like.
b) Brief Description of the Prior Art
It is of common practice to use clamps to fix electrical cables projecting from openings preferably of the knockout type, that are made in a device box. Such clamp is usually L-shaped and attachable to the box by means of a screw insertable into a central opening made in one of its walls. The wall having this opening is shaped so as to define cavities or embossments devised to fit onto and restrain the cable(s) that must be fixed into the box.
It is also well known that the electric cables presently in use can be classified into two different categories including, on the one hand, cables of the "nonmetallic sheathed" type, viz. cables in which the electric wires are embedded into a thick plastic sheathing, and, on the other hand, cables of the "armored" type, viz. cables in which the electric wires extend through and are protected by a metal tube. Examples of such cables of the nonmetallic sheathed and armored types are presently available in the market under the tradenames LOOMEX and BX, respectively.
In addition to the above mentioned structural differences, there is also different standards and requirements for each of these cables. For example, in use, it is compulsory to insert an antishort bushing into the end of an armored cable prior to fix it into a device box, and such a bushing which is made of colored plastic material, must be mounted in such a manner as to visible from the front opening of the device box, thereby making it compulsory to provide openings for this purpose in the clamp used to fix it.
Because of the above mentioned structural differences and requirements, the clamps presently available in the market for fixing nonmetallic sheathed cables are usually different in structure from those used to fix armored cables. In other words, most of the manufacturers offer, on the one hand, device boxed with clamps especially devised to fix nonmetallic sheathed cables and, on the other hand, device boxes with clamps devised to fix armored cables. The consumer must then selected which one of these device boxes he or she needs. Of course, such implies a duplication in the number of parts that the retailers and professionals must keep in stock.
To solve this problem, clamps have been devised by companies like COMMANDER for use with both nonmetallic sheathed and armored cables. Such clamps are very useful but are rather complicated in structure, thereby making their packaging and handling rather complicated on an industrial scale, and their cost rather high because of the amount of metal and the number of manufacturing steps that are needed for their manufacture.